Body support system with energy dissipation means

ABSTRACT

A body support system is provided having improved static and dynamic mechanical response characteristics and improved thermal regulation, and which can provide energy dissipation capabilities. The body support system can be of a modular construction to provide mechanical response characteristics suited to a particular user or group of users, or to a particular environment of use. The energy dissipation characteristics are provided by a flexible fluid compartment containing a volume of viscous fluid, such that at least a portion of the fluid moves within the compartment in response to a vertical force on the compartment.

This is a continuation-in-part application of U.S. Ser. No. 09/882,503,filed Jun. 15, 2001 now U.S. Pat. No. 6,598,251.

BACKGROUND OF THE INVENTION

This invention relates to a body support system such as may be used fora seat cushion. More particularly, this invention relates to a bodysupport system such as may be used for a seat cushion and havingimproved mechanical response characteristics and improved thermalinteraction with a user.

The comfort provided to a user by a body support system such as a seatcushion will depend on a variety of factors. One such factor is themechanical response of the body support system to the compressive andshear forces applied by a user interfacing the body support system,e.g., a user seated on a cushion. Mechanical response includes staticand dynamic responses. Another such factor is the ability of the bodysupport system to provide thermal regulation with a user resulting fromthe inherent heat exchange process/mechanisms in the body supportsystem. If the body support system is to be used in conjunction with amoving vehicle/vessel/device including a wheelchair, a farm implementsuch as a tractor or riding mower, or as a seating element for publictransportation, then the ability of the body support system to provideadequate dynamic response characteristics to applied dynamic excitationsand reduce Whole Body Vibration (WBV) by means of reducing transmissionof harmful frequency components to the user, is another factor.

Conventional contemporary office seats are usually made of eitherupholstered padding or synthetic mesh in a frame assembly. Each of thesetypes of seats has its own characteristic thermal properties. Paddedupholstery (e.g., polyurethane foam) seating provides limited heatexchange with the user, which however mainly occurs through conductionand sweat evaporation processes. As a result, upholstered padding isbetter suited for lower workspace temperatures on the order of 16-25° C.(61-77° F.) and shorter sitting times before heat starts to build up andun-evaporated sweat starts to develop at the user-body support systeminterface On the other hand, mesh seating provides excessive heatexchange between the surrounding environment and the user mainly throughradiation and convection heat exchange processes. In the case of meshseating, these heat exchange processes do not depend on intrinsicproperties of the body support system, but also depend on extrinsicfactors such as surrounding environmental parameters includingtemperature and air speed, and on factors such as workspaceconfiguration, surface orientations, and temperatures and thermalreflectivity of adjacent surfaces such as floor and walls. As a result,mesh chairs may be better suited for higher workspace temperatures of25-35° C. (77-95° F. and longer sitting times. Neither of these priorart seating designs provides for thermal regulation in a wide variety ofoffice temperature environments and workspace configurations.

Another disadvantage of mesh seat upholstery is its tendency to “creep,”that is, to deform viscously or irrecoverably, with disproportionalstress-strain rate characteristics especially in the territrialstress-strain regime, which might be reached (for many meshmaterials)when the user's weight is large, therefore resulting innon-uniform mechanical response to a wide range of users. Creep is asignificant problem when the seat mesh is subjected to heavy sustaineduser's weight over prolonged time. Control of creep usually requirescross directional mesh reinforcement with fibers that have very limitedcreep characteristics. Without proper control, however, creep can causeexcessive deformation in the seat mesh, eventually leading to loss ofcontact at the user-seat interface, and a severe reduction in the totalload carrying capacity of the body support system. This results inexcessive cognitive (conscious and sub-conscious) weight shiftingtowards the front under-thighs and to the feet- and armrests, factorsthat may be directly related to discomfort and unfavorable ergonomicconditions.

Thermal properties are major ergonomic features that should beconsidered in the design of an office chair. The human body always worksto retain its core temperature near 37° C. (98.6° F.), by means such aspostural adjustments, varying skin temperatures such as by perspiration,regulation of cardiovascular and pulmonary activity such as pulse andbreath rates to affect blood flow and vessel sizes especially in skinareas close to a heat-exchanging interface such as that with a seatcushion. A chair that prompts sweating after a relatively short periodof sitting and which requires the human body to engage in such thermalself-regulatory processes will be uncomfortable and may affect workefficiency/productivity. For example, with conventional upholsteredpadding, heat can quickly build up at the user/seat interface causingthe user to limit metabolic rates such as muscular activity to reduceheat generation, therefore severely affecting work efficiency. The usermay also begin sweating to initially expedite the thermal transferacross the user skin, and to attempt to prompt the sweat evaporationcooling process. When the user/seat interface inhibits sweat evaporationdue to low cushion vapor permeability under even small pressures, heatis not dissipated at the interface leading to even greater discomfortfor the user. On the other hand, mesh chairs have high vaporpermeability and heat dissipation and do not allow for any heat build upat the seat user interface. With colder workspace environments, andcloser, oppositely oriented, highly reflective, and cold office spacesurfaces (floors/walls, etc.), and with high (transient or steady)airspeeds, the user is set to become responsible to generate heat thatseeks thermal equilibrium with the whole environment; a condition thatprompts discomfort. This might allow for excessive user heat loss orgain. It is therefore postulated that a limited heat build up at theinterface would be favorable to reverse the thermal gradient across theinterface. Thus, with open mesh seats the thermal comfort of the userbecomes significantly dependent on the ambient temperature of the workenvironment and configuration.

Further, conventional seating designs do not provide for variations inthe size and comfort levels of different users. Different individualswill have different load characteristics and different thermalgeneration rates therefore producing different comfort levels (includingpsychometrics).

It is thus one object of the invention to provide a body support systemsuch as a seat cushion having improved thermal regulation properties.

It is yet another object of the invention to provide a body supportsystem such as a seat cushion having improved mechanical responseproperties including wider low intensity pressure distribution andbetter dynamic response characteristics.

It is also another object of the invention to provide a an energydissipation system as a component of the body of the support system toprovide even greater comfort to a user.

It is still another object of the invention to provide a body supportsystem such as a seat cushion in which the thermal regulation propertiesand/or the mechanical characteristics can be varied to the needs orpreferences of a particular user or group of users by varying amongstthe many design parameters in the system.

SUMMARY OF THE INVENTION

A body support system is provided having improved mechanical (static anddynamic) support characteristics and improved thermal interaction with auser. The improved static support is provided by means for distributingthe weight of a user in response to applied compressive and shear forcesat the user-support system interface. The means for distributing theweight of the user comprises a plurality of vertical columns disposedsubstantially centrally in said body support system. Without connectingthe columns by means of an elastomeric layer, the columns are capable ofdeflecting substantially independently of one another in response to thecompressive forces applied by a user. The improved thermal interactionis provided by structures that provide enhanced airflow through andabout said body support system, thereby providing for convective thermalregulation, and dry and evaporative heat exchange. An elastomeric memberdisposed above said columns also serves to facilitate heat exchange witha user, and cooperates with the columns in the distribution of theuser's weight for improved static and dynamic support. The elastomericlayer acts to level out column deflections, therefore limiting thereaction acting back on the user by an individual column and invoking amore collective response, therefore reducing interfacial pressure peaksand gradients. The improved dynamic response is achieved by dampeningthe peak amplitudes of the response and filtering out harmful frequencycomponents of the dynamic loading. Proportioning the mass and stiffnesssubstantially determines the desirable dynamic response properties ofthe body support system.

The body support system comprises a foam body. In one embodiment, thevertical columns can be configured as upwardly extending risers, formedintegrally with said foam body. In an alternative embodiment, thecolumns can extend downwardly from the elastomeric member. The columnscan be formed of a material having density and mechanical responsecharacteristics either the same as or different from the density andmechanical response characteristics of the foam body. This featurepermits the inventive body support system to be customized to the needsof different users.

The spaces between the vertical columns define a reservoir for a fluidsuch as air within the interior of the body support system. The bodysupport system further comprises means for displacing and/or directingthe flow of fluid, typically air, from the fluid (air)reservoir to theperiphery of the body support system, and then toward the upper surfacethereof, for heat exchange processes with the user, thereby increasingthe comfort of the user when using the body support system for longperiods of time. The means for directing the flow of fluid from thefluid reservoir to the periphery can comprise a plurality of channelsformed within the foam body and extending from the air reservoir to thefoam body periphery. When compressive forces are applied by a user,fluid (air) within the reservoir will be displaced and directed throughthe channels toward the periphery and upwards. Advantageously, airflowthrough the body support system is achieved without the need for activeairflow circulation devices such as fans, blowers, valves, or pumpingdevices. Air deflecting means disposed about the periphery of the foambody function to deflect the air received at the periphery from thereservoir to a region above the foam body for heat exchange with theuser. This thermal regulation function is further enhanced by theaforementioned elastomeric member, which functions as a large capacityheat sink to remove heat from a user generating excessive heat

The body support system of the instant invention can further comprise anair-permeable viscoelastic layer disposed above the elastomeric memberand the foam body. The viscoelastic layer can reduce the transmission ofboth compressive and shear forces to the elastomeric member. Theair-permeable viscoelastic layer can also facilitate the flow ofdisplaced air at the periphery of the cushion to enhance thermalregulation. The airflow achieved with the body support system of theinstant invention also contributes to mechanical function of the bodysupport system by providing recoverable dissipation of applied shear andcompressive forces

The body support system of the instant invention can further compriseenergy modulation means for converting the vertical component of theapplied loading energy, such as a user's weight, to non-vertical, suchas horizontal, dissipative components, which would effectively decreasethe real vertical reaction experienced by a user, therefore enhancingcomfort. In one embodiment, the energy modulation means can comprise amember having a top layer and a bottom layer, each made of a flexiblefluid-tight membrane, the top and bottom layers being joined at theirrespective peripheries to form a bladder, or flexible fluid compartment,having an interior volume, and one or more walls in said interiorvolume, said walls extending between the inner surface of said top andbottom layers to define a plurality of interconnected flexible fluidchambers within said interior volume, said chambers being interconnectedvia baffles, spaces, or minute orifices between and in said walls. Saidinterior volume contains a viscous fluid that can flow in and among thevarious interconnected chambers. When a force such as the weight of auser is applied to the top of the energy modulation means, at least someof the viscous fluid in those chambers directly beneath the force isfurther pressurized and squeezed out from chambers experiencing higherpressurization due to vertical force application to other chambersexperiencing less of such force. The horizontal movement of the viscousfluid between the interconnected chambers dissipates the energy appliedby the user so that the user experiences less resistance and greatercomfort. The energy dissipation means presents many parameters that canbe varied to meet the needs of a particular user or a particular type ofuse. These parameters include, for example, the materials used in thetop and bottom layers and interior walls, the dimensions of the layersand walls, the dimensions of the spaces or orifices interconnecting saidchambers, and the volume and viscosity of the viscous fluid. In analternate embodiment, the flexible fluid compartments may be all fullyconnected to form a full one fluid compartment, filled with viscousfluid that may optionally be pressurized. In another embodiment, suchfull compartment may be depressurized and evacuated from fluid, so thatit can fill with air or fluid pouring into it from an outside source bymeans of an inlet flexible tube, equipped with a one-way valve,therefore, providing means to store such externally pouring fluid, andmeans to later dispose of it, by means of an outlet flexible tube,equipped with a one-way valve, by either using differential staticpressure or by using of micro-pumps attached to such pressurized orun-pressurized fluid containment system. In at least one of theembodiments above, the flexible fluid compartment may be inflated withair of fluid from an external source in order to provide a back reactionon the underside of the said elastomeric layer. Such back reaction wouldtransmit back to the user through the optional overlay, therebyproviding means to stiffen the body support system when needed

The body support system of the instant invention can be used in a widevariety of seating applications. The body support system can beconfigured as a seat cushion such as for use in office seating, in whichcase the seat cushion can be mounted onto a chair frame including apreformed seat pan. The seat pan acts as a high-stiffness or as a rigidsupport for the cushion. The body support system can also be used inrehabilitative seating and other body support applications, such as inwheelchairs, hospital beds, sports cushions, such as in stadiums, andthe like, where improved responsiveness to compressive and shear forcescan help in the prevention of pressure concentrations which might leadto decubitus ulcers. It can also be used in seating or bedding forpersonal assistance purposes such as the case with users confined totheir seats or beds for prolonged periods of time, and requiring readilyavailable fluid containment and management system fully embedded withinthe thinness of the body support system. The inventive body supportsystem can also be used in dynamic situations such as motor vehicles,particularly vehicles driven for long periods of time such as trucks,and even more particularly vehicles driven for long periods of time overuneven surfaces, such as snowplows and farm implements, which vehiclesare subject to motion-induced vibration and in which the vehicle drivercan benefit from the damping of such motion-induced vibration as can beprovided by the inventive body support system disclosed herein.

DESCRIPTION OF THE FIGURES

FIG. 1 is an exploded view of an embodiment of a seat cushion made inaccordance with the instant invention and a seat pan with which it canbe used;

FIG. 2 is a top plan view of the foam body used in the embodiment of theseat cushion of FIG. 1;

FIG. 3 is a cross-section view through line 3—3 of the foam bodyillustrated in FIG. 2.

FIG. 4 is an exploded view of a second embodiment of a seat cushion madein accordance with the instant invention.

FIG. 5 is an exploded view of a third embodiment of a seat cushion madein accordance with the instant invention.

FIG. 6 is a top plan view of an energy dissipation means suitable foruse with a body support system of the instant invention.

FIG. 7 is a cross sectional view of a body support system of the instantinvention including an energy dissipation means.

FIG. 8 is an exploded view of some of the components of FIG. 7.

FIG. 9 is a top plan view of an alternative embodiment of an energydissipation means suitable for use with the instant invention.

FIG. 10 is a top plan view of yet another alternative embodiment of anenergy dissipation means suitable for use with the instant invention.

FIG. 11 is a perspective view of still another embodiment of an energydissipation means suitable for use with the instant invention.

DETAILED DESCRIPTION OF THE INVENTION

The figures herein illustrate various embodiments of the inventionwherein the body support system is in the form of a seat cushion such asfor use with an office chair. It will be understood that theseembodiments are presented herein for illustrative purposes only, andthat the inventive body support member can be used in other embodimentsand for other purposes, as discussed below.

FIG. 1 is an exploded view of a first embodiment of a seat cushion bodysupport member 10 of the instant invention. Seat cushion 10 comprisesfoam body 12, illustrated in FIGS. 1-3. Foam body 12 can be formed ofmaterials typically used in such seat cushions, such as open-celled orclosed-celled polyurethane foam. Foam body 12 has an upper surface 13and a plurality of vertical columns 15 disposed substantially centrallyin said foam body 12. In the illustrated embodiment, the columns 15extend upwardly such that the top surface of said columns 15 define aplanar curved surface that is substantially parallel to upper surface13. In the embodiment illustrated in FIGS. 1-3, the columns 15 areformed integrally with foam body 12. The foam material of which foambody 12 and columns 15 are made will be resiliently deformable to someextent. The columns 15 are structured such that, in the absence of otherstructural elements of the body support member 10, each column 15 iscapable of deflecting substantially independently of the other columns15 in response to compressive forces applied by a user.

Vertical columns 15 are structured so as to define a plurality of airspaces 16 therebetween, which together define a plenum or reservoir 18for a fluid such as air. A plurality of channels 20 disposed within foambody 12 extend from air reservoir 18 toward the periphery of foam body12. In the illustrated preferred embodiment of a seat cushion, thechannels 20 are directed to the front and lateral sides of the foam body12.

Design parameters of vertical columns 15 include their number, planarspacing, depth, aspect ratios, and material density and stiffness.Depending on their size and shape, the number of vertical columns can bein the range of about 5-180 columns, more preferably in the range ofabout 30-90 columns, and even more preferably about 40-80 columns. Thecolumns can have a diameter at their lower end in the range of about0.5-4.0 inches, more preferably in the range of about 0.75-3.0 inches,and most preferably in the range of about 1.0-2.0 inches. The columnscan have a diameter at their upper end in the range of about 0.5-4.0inches, more preferably in the range of about 0.75-3.0 inches, and mostpreferably in the range of about 0.9-2.0 inches. The height of thecolumns can range up to about 4 inches, more preferably will be in therange of about 0.5-3.0 inches, and most preferably will be in the rangeof about 0.5-1.5 inches. The columns 15 in a seat cushion 10 can be ofdifferent sizes and shapes.

The number of air channels 20 will depend upon their size. For example,in the illustrated embodiment, the channels 20 directed toward the frontedge of the chair are of different sizes with one large channel in thecenter and three smaller channels on either side of the large channel.Similarly, the channels 20 directed toward the sides of the chair can beof predetermined size and n. The total volume capacity of channels 20will be a function of the volume capacity of air reservoir 18.

The seat cushion 10 further comprises an elastomeric layer 30 thatoverlays the upwardly extending risers 15. In the illustratedembodiment, the periphery 31 of elastomeric layer 30 is seated withinfitting edge 14 at the upper surface 13 of foam body 12. Elastomericlayer 30 comprises a top surface 32 and a bottom surface 34. Bottomsurface 34 of elastomeric layer 30 defines the top surface of airreservoir 18. Elastomeric layer 30 comprises a material havingsignificant resilience and flow properties. Suitable materials forelastomeric layer 30 include, for example, a gelatinous sheet and apolymeric membrane, or other gelatinous materials with variableviscoelastic properties. One suitable material includes a gel sold underthe trademark LEVAGEL® by Royal Medica of Italy. Information about thismaterial is available at www.royalmedica.it. Elastomeric layer 30 andupwardly extending risers are each characterized by both an elasticstiffness value and a dissipative stiffness value. The elastomeric layer30 may be reinforced with textile fabric sheets placed within thethickness of such elastomeric layer or adhered onto it from either orboth sides. Such reinforcement might include pre-tensioning fabricfibers or post-tensioning those with the gelatinous material. In apreferred embodiment of the invention, the ratio of elastic stiffness todissipative stiffness of the vertical columns 15 is greater than theratio of elastic stiffness to dissipative stiffness of the elastomericlayer 30.

Depending on the material selected, the application of the body supportsystem, and the properties of the body support system desired,elastomeric layer 30 can have a thickness in the range of about 0.1-1.5inches, more preferably in the range of about 0.1-0.5 inches, and mostpreferably in the range of about 0.2-0.4 inches. As illustrated in FIG.1, the area of elastomeric layer 30 can be less than the area of topsurface 13. The relative area of elastomeric layer 30 to top surface 13can be in the range of about 20-95%, more preferably in the range ofabout 25-60%, and most preferably in the range of about 30-55%. In oneembodiment, elastomeric layer 30 is about 0.25 inches thick, and has anarea of 210 sq. in., relative to a total area of top surface 13 of 392sq. in.

In use, the foam body 12 of seat cushion 10 is supported by a stiff seatpan 25 fixed on a seating system (not shown). In the illustratedembodiment, seat pan 25 comprises an inner pan 26 bolted to pan support27. Pan support 27 can be made of glass-filled nylon, for example, andpreferably includes a plurality of support ribs 28. When a user isseated on a seat cushion of the instant invention, the user's weight istransmitted as vertical compressive forces and transverse shear forcesto the user/seat cushion interface. These forces are transmitted throughelastomeric layer 30 to vertical columns 15. Elastomeric layer 30 andvertical columns 15 function cooperatively with one another to achieve adesired self-limiting mechanical response. As a result of the ratios ofelastic stiffness to dissipative stiffness of the columns 15 andelastomeric layer 30, each column 15 responds substantially in themanner of an elastic spring with weak dissipation, analogous to variousengineering models of springs and dashpots. Highly localized compressiveforces at the seat/user interface would result in undesirable pressurepeaks, resulting in greater deformation of the columns 15 in thatparticular location, i.e., each column is expected to deform in directproportion to the applied forces to that column. The elastomeric layer30 mitigates these ergonomically undesirable effects by deforming inresponse to the applied forces, partially dissipating the applied forcesand causing elastic transfer of excess applied force to neighboring orremote columns 15. The applied forces are distributed to neighboring orremote columns 15 to obtain a more even pressure distribution. Thus,elastomeric layer 30 creates interdependence of the column deflectionsby transmitting stresses resulting from differential column deflections,by elastic and dissipative means, thereby limiting individual columndeflections, and the corresponding column reaction on the user's body inthat pressure-peak locality, in a pre-determined manner. The verticalforce due to a user-imposed loading would be reacted by vertical columnreactions and by vertical projections of the elastic and dissipativetension in the elastomeric layer, thereby reducing the back reaction(pressure) intensity of the real vertical reaction experienced by theuser. In accordance with the invention, the materials and geometricfeatures of the elastomeric layer 30 and columns 15 may be selected toproduce the level of applied force redistribution desired for aparticular user or a particular type of seating application.

The redistribution of applied forces can be further enhanced byair-permeable layer 35, disposed above elastomeric layer 30.Air-permeable layer 35 may comprise an open-cell or non-wovenviscoelastic material having specified thickness and viscoelasticproperties, which air-permeable layer 35 can function to furtherdissipate applied forces before such forces reach elastomeric layer 30.Optionally, an intermediate foam layer 37 can be placed betweenair-permeable layer 35 and elastomeric layer 30. A cover fabric, notshown, can overlie the entire seating structure. The layers 12, 30, 37,35, and the cover fabric can be pre-bonded to one another such as withadhesives. Alternatively, the layers can simply be stacked on top ofeach other, in which case there should be a sufficient amount offriction between the layers to prevent slippage of the layers withrespect to one another in response to shear forces applied during use.

The structure of the instant invention will transmit shear forcesemanating at the user/seat interface across the interfaces between eachof the layers until elastomeric layer 30. Elastomeric layer 30 willdeform viscously in response to applied shear forces, therebycounteracting the shear component of the user's weight and/or appliedloads by dissipative means, such that the user's skin will notexperience the real elastic shear component. As a result, the user'stissues will experience substantially only compressive stresses in thenormal direction. This reduction in shear stress can reduce tissuestraining and distortion, and therefore could reduce the potential forthe development of pressure ulcers, and reduce undesirable interferencewith blood vessel activity in the vicinity of these tissues.

When the user leaves the seat cushion of the instant invention, theresiliency of the foam body 12, vertical columns 15 and the elastomericlayer 30 allows full recovery of both shear and compressiondeformational mechanisms of the cushion. The passive air pumpdepressurizes, allowing outside air to pass through the outside cover,the air permeable layer, and optional intermediate foam layer to enterthe air reservoir and channels, and open cells in the foam body 12 ifopen-celled foam is used. The elastomeric layer 30 will also return toits original shape prior to the application of compression and shearforces by a user.

The body support system of the instant invention provides both dynamicand static support. User discomfort in dynamic seating situations ariseswhen vibrations are transmitted through a seating system to the user,such as in vehicle or public transportation seating systems. Themulti-layer structure of the inventive body support system providesenhanced dynamic support by filtering out harmful higher frequencycomponents in the compressive and shear vibration modes. Each of thebody support system elements, namely, the foam body, the verticalcolumns, the elastomeric layer, and the air permeable layer, cancontribute to the vibration filtering process. The materials for theseelements, and the size and shape of these elements, can be selected toprovide dynamic support characteristics for a particular environment inwhich the body support system will be used. Static support will be afunction of the stiffness of the components, and particularly thestiffness of the vertical columns.

The inventive body support system also provides improved thermalinteraction with a user. This is achieved through several means. Theinventive body support system promotes thermal exchange between the useras a heat source and the body support system as a heat conduit and heatsink. This heat exchange is achieved partially through convection,facilitated by air exchange. In the embodiment in which the body supportsystem is a seat cushion, when the seat cushion is not in use, airreservoir 18 and air channels 20 are filled with air, as are the cellsof foam body 12. When a user occupies the seat and applies compressiveand shear forces to seat cushion 10, air is forced from air reservoir 18through air channels 20 from which it is reflected back to the regionbetween elastomeric layer 30 and air-permeable layer 35. Some air mayalso permeate directly from air channels 20 through air-permeable layer35 or to cover fabric. Air-permeable layer 35 serves to diffuse the airtoward the user to facilitate heat exchange and promote user comfort.Air permeable layer 35 also allows air/vapor permeation from the user tothe seat cushion, where air/vapor and heat can pass throughair-permeable layer 35 to elastomeric layer 30, which then acts as aheat sink. This airflow at the user/seat interface also allows forevaporation which enhances the cooling effects and further promotes usercomfort.

To facilitate heat exchange, the optimal air-permeable layer 35 willhave pre-selected fiber directionality and anisotropic air-permeability,depending on the particular application of seat cushion 10. In addition,air-permeable layer 35 can be treated with phase changing materials tofurther regulate heat exchange processes at the user/seat interface.Such phase change materials, generally in the form of tiny capsules,will be such size and packed in such a way that the microporosity ofair-permeable layer 35 will not be affected. Suitable phase changematerials include those commercially available from OutlastTechnologies, Inc. of Boulder, Colo., and those described in U.S. Pat.No. 6,207,738 assigned to Outlast Technologies, Inc. Air-permeable layer35 also may be formed from multiple layers of material.

Generally, in each of the embodiments disclosed herein, thermalregulation can be enhanced by 1) the cellular construction of the foambody; 2) the airflow circulation generated by the structures of thecomponents of the body support system; 3) the large heat storagecapacity of the elastomeric layer; 4) the thermal conductive propertiesof the materials selected; 5) the use of phase-change materials, and 6)the microporosity and air-permeable qualities of the cover fabric, andall the layers above the elastomeric layer.

The body support system of the instant invention thus allows convectiveheat transfer to occur along with, or in lieu of, conductive,evaporative, and/or radiative heat transfer processes such as thoseoccurring with prior art devices. The favorable thermal properties arefurther achieved by pressurized air circulation mechanisms as a resultof deformation of vertical columns 15. Advantageously, this aircirculation may be achieved without airflow valves or fans, and withoutexternally powered air pumps.

FIG. 4 illustrates an alternative embodiment of a seat cushion of theinstant invention. Seat cushion 110 comprises foam body 112. Foam body112 can be formed of materials typically used in such seat cushions,such as open-celled or closed-celled polyurethane foam. Foam body 112has an upper surface 113 and a plurality of vertical columns 115disposed substantially centrally in said foam body 112 such that the topsurface of said columns 115 define a curved surface substantiallyparallel to that of upper surface 113. In the embodiment illustrated inFIG. 4, the columns 115 are formed integrally with foam body 112. Thefoam material of which foam body 112 is made will be resilientlydeformable to some extent. The columns 115 are structured such that eachcolumn 115 is capable of deflecting substantially independently of theother columns 115 in response to compressive forces applied by a user.

Vertical columns 115 are structured so as to define a plurality of airspaces 116 therebetween, which together define a plenum or air reservoir118. A plurality of channels 120 are disposed within foam body 112, andextend from air reservoir 118 toward the periphery of foam body 112.

The seat cushion 110 further comprises an elastomeric layer 130 thatoverlays the vertical columns 115. In the illustrated embodiment, theperiphery 131 of elastomeric layer 130 is seated within fitting edge 114at the upper surface 113 of foam body 112. Elastomeric layer 130comprises a top surface 132 and a bottom surface 134. Bottom surface 134of elastomeric layer 130 defines the top surface of air reservoir 118.Elastomeric layer 130 comprises a material having significant resilienceand flow properties. Suitable materials for elastomeric layer 130include, for example, a gelatinous sheet and a polymeric membrane, orother gelatinous materials with variable viscoelastic properties.Elastomeric layer 130 and vertical columns 115 are each mechanicallycharacterized by both an elastic stiffness value and a dissipativestiffness value. In a preferred embodiment of the invention, the ratioof elastic stiffness to dissipative stiffness of the columns 115 isgreater than the ratio of elastic stiffness to dissipative stiffness ofthe elastomeric layer 130. Elastomeric layer 130 will function in amanner analogous to that of elastomeric layer 30 in the embodiment ofFIGS. 1-3.

The embodiment of FIG. 4 further comprises seat pan 125 andair-permeable layer 135, the structures and functions of which areanalogous to those of seat pan 25 and air-permeable layer 35 in theembodiment illustrated in FIGS. 1-3.

The embodiment of FIG. 4 is characterized by modular insert 142 havingvertical columns 145. Modular insert 142 has a perimeter 141 that willbe sized and shaped to fit within the foam body 112. Modular insert 142can be made of the same material as foam body 112, or modular insert 142can be made of a material wherein the ratio of elastic stiffness todissipative stiffness is greater than or less than that of the materialof which foam body 112 is made. Further, the size and shape of columns145 can be the same as or different from the size and shape of columns115. The choice of materials to be used in the manufacture of modularinsert 142, and the design of the size and shape of columns 145, permitthe seating designer to select from a variety of mechanical and thermalproperties, achieved by varying the modular construction, for the seatcushion 110 of the instant invention.

FIG. 5 illustrates yet another embodiment of a seat cushion made inaccordance with the instant invention. Seat cushion 210 comprises foambody 212. Foam body 212 can be formed of materials typically used insuch seat cushions, such as open-celled or closed-celled polyurethanefoam. Foam body 212 has an upper surface 213 and a plurality of verticalcolumns 215 disposed substantially centrally in said foam body 212 suchthat the top surface of said columns 215 define a curved surfacesubstantially parallel to upper surface 213. In the embodimentillustrated in FIG. 5, the columns 215 are formed integrally with foambody 212. The foam material of which foam body 212 is made will beresiliently deformable to some extent. The columns 215 are structuredsuch that each column 215 is capable of deflecting substantiallyindependently of the other columns 215 in response to compressive forcesapplied by a user on a contributory area of the user-seat interface thatexists above the locality of that column/riser.

Vertical columns 215 are structured so as to define a plurality of airspaces 216 therebetween, which together define a plenum or air reservoir218. A plurality of channels 220 disposed within foam body 212 extendfrom air reservoir 218 toward the periphery of foam body 212.

The seat cushion 210 further comprises an elastomeric layer 230 thatoverlays the vertical columns 215. Elastomeric layer 230 comprises a topsurface 232 and a bottom surface 234. Bottom surface 234 of elastomericlayer 230 defines the top surface of air reservoir 218. Elastomericlayer 230 comprises a material having significant resilience and flowproperties. Suitable material for elastomeric layer 230 include, forexample, a gelatinous sheet and a polymeric membrane, or othergelatinous materials with variable viscoelastic properties. Elastomericlayer 230 and upwardly extending risers are each characterized by bothan elastic stiffness value and a dissipative stiffness value. In apreferred embodiment of the invention, the ratio of elastic stiffness todissipative stiffness of the columns 215 is greater than the ratio ofelastic stiffness to dissipative stiffness of the elastomeric layer 230.

The embodiment of FIG. 5 further includes periphery edge component 250designed to fit within fitting edge 214 of foam body 212, which edgesurrounds the region of foam body 212 where vertical columns 215 areformed. In this embodiment, elastomeric layer 230 is also sized andshaped to fit within periphery edge component 250. Periphery edgecomponent 250 thus serves to securely locate elastomeric layer 230directly over vertical columns 215, thereby assuring that compressiveand shear forces exerted by a user through elastomeric layer 230 will betransmitted to upwardly extending risers 215. In addition, peripheryedge component 250 helps to define air reservoir 218, and can functionas an airflow diffuser. Periphery edge component 250 can be made ofmaterials such as open-cell polyurethane or non-woven syntheticmaterial. Periphery edge component 250 can also be used in thoseembodiments of the invention that employ modular insert 142 illustratedin FIG. 4.

FIGS. 6, 7, and 8 illustrate yet another embodiment of the instantinvention wherein the body support system of the instant inventionfurther comprises energy modulation means 320 for converting thevertical component of the applied energy of a user's weight tononvertical, such as horizontal dissipative components, which wouldeffectively decrease the real vertical reaction experienced by a user,therefore enhancing comfort. In one embodiment, the energy modulationmeans 320 can comprise a top layer 322 and a bottom layer 324 each madeof a flexible fluid-tight membrane, the top and bottom layers beingjoined at their respective peripheries to form a bladder or flexiblefluid chamber 328 having an interior volume 330, and one or more walls332 in said interior volume 330, said walls extending between the innersurfaces of said top and bottom layers 322, 324 to define a plurality ofinterconnected chambers 334 within said interior volume 330, saidchambers being interconnected via connection means 335 such as baffles,spaces or minute orifices between or in said walls. Said interior volume330 contains a viscous fluid 336 that can flow in and among the variousinterconnected chambers 334 via said connection means 335. When a forcesuch as the weight of a user is applied to the top of the energymodulation means 320, at least some of the viscous fluid 336 in chambers334 directly beneath the force is further pressurized and squeezed outfrom chambers experiencing higher pressurization due to vertical loadapplication to other chambers experiencing less of such force. Thehorizontal movement of the viscous fluid 336 between the interconnectedchambers 334 dissipates the energy applied by the user so that the userexperiences less real reaction and greater comfort.

In an alternate embodiment illustrated in FIG. 9, a bladder 360 has nointernal walls 332 but instead is in the form of one flexible fluidcompartment, filled with viscous fluid that may optionally bepressurized. Bladder 360 can be provided with a valve 362 for eitherfilling or emptying the fluid from the bladder.

In another embodiment illustrated in FIG. 10, compartment 370 may bedepressurized and evacuated from fluid, so that it can fill with air orother fluid added into it from an outside source by means of an inletflexible tube 372 equipped with a one-way valve 374, therefore,providing means to store such externally added fluid, and means to laterdispose of it, by means of an outlet flexible tube 376, equipped with aone-way valve 378, by either using differential static pressure or byusing of micro-pumps attached to such pressurized or un-pressurizedfluid containment system.

When used in conjunction with a body support system such as the seatcushion illustrated in FIG. 1, energy dissipation means 320 can be mostpreferably be positioned in between vertical columns 15 and beneathelastomeric layer 30, or above elastomeric layer 30 and beneath optionalintermediate foam layer 37, or directly beneath air permeable layer 35.Alternatively, energy dissipation means 320 can be configured to have aplurality of orifices 340 extending therethrough, said orifices 340being positioned and dimensioned to receive vertical columns 15 suchthat energy dissipation means 320 surrounds at least part of thevertical length of columns 15 and at least takes up part of the space ofair reservoir 18.

The viscous fluid 336 can be contained completely within the energydissipation means. Alternatively, viscous fluid can flow betweeninterior volume 330 and an external fluid reservoir via one or moretubes 342, generally indicated in FIG. 11.

Energy dissipation means 320 can be made of any suitable material suchas plastic sheets or air-impermeable flexible membranes, which areflexible, and both inert and impermeable to the viscous fluid used. Thematerial should also retain its strength and flexibility over thetemperature and pressure conditions in which the body support systemwill be used. Gelatinous, Polyethylene, or Polyvinyl chloride aresuitable materials for most applications. The viscous fluid can be anyinert fluid that maintains viscosity in an acceptable range in thetemperature and pressure conditions in which the body support memberwill be used. The viscous fluid should have a scale Shore A hardness ofabout 1-15, preferably about 3-10, and most preferably about 4-8.Mineral oil is one suitable viscous fluid for many application of theinstant invention.

The energy dissipation means presents many parameters that can be variedto meet the needs of a particular user or a particular type of use.These parameters include, for example, the materials used in the top andbottom layers and interior walls, the dimensions of the layers andwalls, the dimensions of the spaces or orifices interconnecting saidchambers, and the volume and viscosity of the viscous fluid. The energydissipation means 320 can be provided with orifices, baffles, and/orvalves disposed between the various chambers 334 or between the interiorvolume 330 and the tubes 342, or between the tubes 342 and the fluidreservoir. In one embodiment, the opening size of these orifices orvalves may be externally controlled by the user to provide the level ofenergy dissipation desired.

The many parameters of energy dissipation means 320 allow it to beadapted to a variety of static and dynamic uses. Energy dissipationmeans 320 can be used on dynamic seating situations such as farmimplements and snowplow trucks to dampen or eliminate vibrationfrequencies that can be harmful to a user. Energy dissipation means 320also can be made quite thin while still providing effective protectionfor a user. This makes the energy dissipation means particularly wellsuited to applications such as wheelchairs and gurneys. Still otherapplications include floor mats for persons who stand for long periodsof time, athletic pads, and floor and wall cushions for athletic venuesand the like.

In each of the embodiments of the instant invention described above, thefluid flow resulting from the structural design and choices of materialsfor each of the component parts results in two important effects. First,the fluid flow contributes to the thermal regulation function at theuser/seat cushion interface substantially through enhanced convection.Second, the fluid flow provides important mechanical effects, in thatthe fluid flow pumping generates a delay in the cushion responses ofdeformation and recovery due to loading and unloading of the user'sweight. The modular construction of the seat cushion allows the seatingdesigner to choose materials and designs for each of the component partsthat will provide both the thermal properties and the mechanicalproperties desired for a particular application. Thus the seat cushionof the instant invention is adaptable to a wide variety of uses. Forexample, the seat cushion can be designed for static uses, such asoffice seating, or for rehabilitative seating such as wheelchairs, orfor dynamic uses in which damping of vibrations is an important feature,such as trucks, public transportation seating, farm implements,construction trucks, forklifts, and snowplows.

In yet another embodiment, the fluid in reservoir 18 and channels 20need not be air, but can be some other fluid such as electricallyinduced polymer gels, or electro-rheological fluids that change betweensolid and liquid phase and/or change colors in response to astress-generated electric field in the fluid or due to heat effects.Electric fields in the fluid also can be generated by piezo electricelements at the vertical columns.

There have been disclosed several embodiments of a body support systemhaving improved mechanical response characteristics and improved thermalregulation. Those skilled in the art will recognize that otherembodiments can be made using obvious variations of the disclosedembodiments, and such variations are intended to be within the scope ofthe claims appended hereto.

We claim:
 1. A body support system comprising a) a compressible, resilient foam body comprising a fluid reservoir means for directing the flow of fluid from said fluid reservoir toward the periphery of the body support system when a region of said body support system is compressed by a user, b) elastomeric means for distributing a load applied to said body support system by a user, and, c) an energy dissipation means, said energy dissipation means comprising a flexible fluid compartment, said flexible fluid compartment containing a volume of a viscous fluid, such that at least a portion of said fluid moves within said flexible fluid compartment in response to a vertical force on said flexible fluid compartment wherein said foam body comprises a plurality of vertical columns, and said flexible fluid compartment is configured to have a plurality of orifices extending therethrough, said orifices being positioned and dimensioned to receive said vertical columns and surround at least a portion of the vertical length thereof.
 2. The body support system of claim 1 wherein said flexible fluid compartment comprises a plurality of interconnected chambers, such that said viscous fluid moves from one to another of said chambers in response to a vertical force on said flexible fluid compartment.
 3. The body support system of claim 1 wherein said flexible fluid compartment is disposed above said resilient foam body.
 4. The body support system of claim 1 further comprising a reservoir in fluid communication with said flexible fluid compartment.
 5. The body support system of claim 1 further comprising valves adapted to control the flow of fluid within said flexible fluid compartment.
 6. The body support system of claim 1 wherein said viscous fluid has a scale Shore A hardness in the range of about 1-15.
 7. The body support system of claim 1 wherein said viscous fluid is mineral oil.
 8. A body support system comprising: a compressible, resilient foam layer having a central region; a plurality of spaced apart structural elements defining a fluid reservoir in said central region; a plurality of fluid channels in said foam layer in communication with said fluid reservoir for communicating fluid into and out of said fluid reservoir; an elastomeric layer disposed above said central region of said foam layer, above said structural elements and above said fluid reservoir, said elastomeric layer having resilience and flow properties; and an energy dissipation means, said energy dissipation means comprising a flexible fluid compartment, said flexible fluid compartment containing a volume of a viscous fluid, such that at least a portion of said fluid moves within said flexible fluid compartment in response to a vertical force on said flexible fluid compartment.
 9. The body support system of claim 8 wherein said foam layer comprises an upper surface; and said plurality of fluid channels is formed in said upper surface and extends from said fluid reservoir.
 10. The body support system of claim 8 wherein said plurality of spaced apart structural elements comprises a plurality of vertical columns, and wherein said elastomeric layer distributes load applied to said body support member by a user and is disposed above said columns and in cooperative engagement therewith.
 11. The body support system of claim 10 wherein said elastomeric layer comprises a viscoelastic gel.
 12. The body support system of claim 10 further comprising means for directing the flow of fluid from said reservoir toward a central area of said body support system disposed above said elastomeric layer.
 13. The body support system of claim 12 wherein said means for directing the flow of fluid comprises an air-permeable layer disposed above said elastomeric layer; and said fluid is air.
 14. The body support system of claim 12 further comprising an intermediate foam layer disposed between said air-permeable layer and said elastomeric layer.
 15. The body support system of claim 8 further comprising a cover fabric.
 16. The body support system of claim 8 being in the form of a seat cushion.
 17. The body support system of claim 16 wherein said seat cushion is adapted for use in a moving vehicle.
 18. The body support system of claim 15 wherein said fabric comprises a phase change material.
 19. The body support system as claimed in claim 8 wherein said fluid is air; and including an air-permeable layer disposed above said elastomeric layer for diffusing air to and away from a body on said system.
 20. A body support system comprising: a) a foam body; b) a plurality of resilient vertical members having air spaces therebetween, said resilient vertical members each being independently deformable; c) an elastomeric member disposed over said resilient vertical members and in contact therewith, d) an air-permeable layer disposed over said elastomeric member, e) a cover providing an interface between said body support member and a user; and f) an energy dissipation means, said energy dissipation means comprising a flexible fluid compartment, said flexible fluid compartment containing a volume of a viscous fluid, such that at least a portion of said fluid moves within said flexible fluid compartment in response to a vertical force on said flexible fluid compartment; said foam body, plurality of vertical members, elastomeric member, air-permeable and cover being in cooperative assembly such that when a user exerts a force on said body support member, the force causes air to flow from said air spaces between said resilient vertical members to a region above said elastomeric layer and through said air-permeable layer to said interface with the user.
 21. The body support system of claim 20 wherein said vertical members extend upwardly from said foam body.
 22. The body support system of claim 20 wherein said vertical members extend downwardly from said elastomeric member.
 23. The body support system of claim 20 wherein said foam body has a plurality of channels formed therein, said channels facilitating the flow of air from said air spaces to said interface.
 24. The body support system of claim 20 wherein said elastomeric layer comprises a gelatinous material and a polymeric membrane.
 25. The body support system of claim 20 further comprising a cover fabric.
 26. The body support system of claim 25 wherein said fabric comprises a phase change material.
 27. A body support system comprising: a first layer having resilience and flow properties for damping and distributing applied forces from the weight of a user's body and to reduce shear on said body; and a second layer located beneath said first layer and in operative communication therewith, said second layer having a region with a boundary, a plurality of structures deformable and responsive to compressive forces spaced about in said region, said region also forming a fluid reservoir, and a plurality of fluid passages communicating said fluid reservoir beyond said boundary and beyond said first layer for thermal effects; an energy dissipation means, said energy dissipation means comprising a flexible fluid compartment, said flexible fluid compartment containing a volume of a viscous fluid, such that at least a portion of said fluid moves within said flexible fluid compartment in response to a vertical force on said flexible fluid compartment; and wherein structures of said plurality of structures are each generally independent of one another and are responsive to localized forces when applied forces on said first layer are absent, and when applied forces are present on said first layer, said first layer distributes said applied forces such that structures under said applied forces as well as neighboring structures are exposed to compressive forces.
 28. The body support system claimed in claim 27 wherein fluid from said fluid reservoir removes heat from said first layer, which heat is generated by the user's body.
 29. The body support system as claimed in claim 28 including an air-permeable layer disposed above said first layer for diffusing air to and from said user's body; and wherein said fluid is air. 